Tuesday, January 26, 2010

Its been awhile since I've done a "creature feature"..so today, I give you the "Basket Star"aka Gorgonocephalus!! Go here for a photoessay.

Gorgonocephalus belongs to the class OPHIUROIDEA, that is, it belongs to the same group as the more typical 5-armed "brittle stars" you may be more familiar with. Such as the one here and the ones here.

Gorgonocephalus occurs mainly in cold-water environments, and is found in the Arctic, the Antarctic and in the deep-sea throughout the world. Although, shallow in some places (such as Alaska, Canada, etc.) it is found mostly in deep-water. There are about 10-12 species (look them up here). Good luck telling them apart though. Many are VERY similar in appearance and are distributed over a wide range...

Unlike most other ophiuroids, the special "basket star" and "serpent star" group have a VERY different arm structure related to how they feed. For example:

1. Arm structure in basket stars has a thick, fleshy covering over the basket star endoskeleton. If we look at a cross-section through the arms, we see in green that there is an exterior leathery "skin" that completely covers the calcium carbonate "ossicles" aka vertebrae that compose the arm structure....and here's the rest of it! (with skin removed from vertebrae-like endoskeleton)2. Arm structure (i.e., the vertebrae-like endoskeleton) in this group SPLITS (aka bifurcates) instead of staying in a single linear series.There's a whole bunch cool stuff about Gorgonocephalus, the least of which is its NAME, which literally translates into "Gorgos" and "-cephalus" aka the Greek for "Gorgon's Head" named for the fearsome monsters (e.g., Medusa) with snakes for hair whose gaze could turn people to stone!!....and here is one for comparison!Remarkably little is known about these animals. But there are some GREAT feeding studies on Gorgonocephalus, including this recent one by Rosenberg et al., (2005) and this earlier one by Emson et al. (1991). So, let's look at that!

FEEDING in Gorgonocephalus is relatively straightforward. They sit on perches, often corals, sponges, rocks or sometimes just on the seafloor bottom like this:

Gorgonocephalus feed mostly on small crustaceans and similar critters, such as the "northern krill" Meganyctiphanes norvegica . That's in contrast to other kinds of "filter feeders", like crinoids, that pick up small to microscopic food particles.

Functionally, this makes basket stars-PREDATORS! Pretty weird ones, when you think about it..

Bear in mind that the arms are covered with HOOKS and SPINES! Here is a closeup....

(Fig. 2 from Rosenberg et al., 2005)

These hooks function along with spines and the tube feet to capture (i.e., snag and snare)prey that get too close! and work it down to the mouth...Which, represents the SECOND echinoderm-thing that kinda looks like the Sarlacc pit from Return of the Jedi!! (or maybe the Sarlacc is just a giant desert Gorgonocephalus???)The studies I read suggest that Gorgonocephalus prefers a pretty mellow current.

Rosenburg et al. (2005) mention that in high current speeds (> 50 cm/second) these animals have difficulties keeping their arms stretched out and the number of curled arms increased, which they believe will decrease drag!!!

If the "Force" from Star Wars was real, it would be carbon. It binds, us and ties all living things together. Where it gets built up or "sequestered" can be an important consideration for understanding these global cycles.

It sequesters or stores carbon as part of the process of recycling it back into the water column and beyond! But up til' now, the contribution of carbon to this system was poorly understood.

When echinoderms die (i.e. decompose), their bodies fall apart (i.e., disarticulate) and those carbonate pieces fall into and are buried into the sea bottom and begin the "carbon cycling" process.Lebrato et al. found that on a global scale, echinoderms have a PRODUCTION rate of approximately .861 Pg of CaCO3 (Pg=petagrams=1 billion metric tons!) per year!!So echinoderms produce just short of of 1 billion metric tons of calcium carbonate a year!!

The amount of echinoderm carbonate, which is right now, present on ocean bottoms aka the "Standing stock" is about 2.11 Pg of CaCO3 from organisms on the continental shelves, slopes and abyssal depths (1000+ m).

Apparently, more then 80% of global calcium carbonate production from echinoderms comes from animals that occur between 0 and 800 meters!! With the highest amounts attributed to the shelf and upper slope.

The greatest amount of standing stocks included ophiuroids (i.e., brittle stars)....asteroids (aka starfish or sea stars)and sea urchins...LeBrato et al. calculated "standing stocks" (i.e., the amount present today) from all around the world with different species making up the overall CaCO3 standing stocks in different parts of the world. Much variation exists.

Apparently, more then 80% of the substantial CaCO3 stocks were found in shallower then 800 m depths, especially from 0 to 500 m.

To refine the number above, echinoderms "sequester" or "capture" about 0.1 gigatons of carbon per year. This is apparently MORE then is "captured" by benthic foraminifera but less when compared against what is "captured" by pelagic (those that live in the open ocean) organisms, which capture about 0.4 to 1.8 gigatons.

By comparison, human activities produce about 5.5 gigatons of carbon every year.

Perhaps most critical is that the authors have found that there are regions around the world where the minerals used to form calcium carbonate are undersaturated (i.e., not as rich in the minerals needed to from calcium carbonate).

The authors attribute this directly to ocean acidification with the gravest concern of what should happen when this reaches the richest "standing stock" areas (i.e., where the bulk of echinoderms occur).

So, we are now JUST learning about the importance of carbon (in the form of calcium carbonate) that is "built up" on the sea bottoms (i.e., the benthos). What happens if this cycle is interrupted? Will the loss of carbon (in the form of calcium carbonate) sequestered on the sea bottoms result in ecological changes or worse??Time will tell...but for now, we now how important it is to look at echinoderms on the deep-sea bottoms....

Thursday, January 14, 2010

Today, MORE Exotic Hawaiian starfishes sent to me to ID!! Thanks to Gordon Hendler (Los Angeles County Museum) who found the specimens and Cory Pittman, who photographed the specimens!

Let me caveat that Astropecten (family Astropectinidae) is VERY hard to identify from pictures! In a professional sense, having vouchers is the best way to ID them..

First, Astropecten polyacanthus Like all Astropecten (there are 2 in shallow-water Hawaii), this species burrows into the sea bed and live under a fine veneer of unconsolidated sediment, where they feed on various small, molluscan fare..snails, clams, etc.

This beast is about 2 inches in diameter and was collected in Maui from about 9.0 m. It is distinguished from the 2nd species by having spines in each interradius and adults should only have one spine per superomarginal plate (but this is difficult from pictures)A second specimen (also discovered by Hendler/ photographed by Pittman) from Maui at about 10 m is possibly a Astropecten triseriatus myobrachius. This specimen was only about an inch in diameter.This species differs slightly, in having 2-3 spines per plate and is missing the spines pointing aborally (i.e., upward) in each interradius..

Although, this seems like A. t. myobrachius to me, its entirely possible that this is some kind of juvenile of the species above with smaller features.THESE are the kinds of FACTORS that make taxonomic identification difficult (and challenging)!Valvaster striatus (family Ganeriidae), has been known for awhile (described by Lamarck in 1816) but we know NOTHING about it except for the name.Its definitely a RARELY encountered, but thankfully, easy to identify, species in Hawaii (known from Oahu and Maui), but is known widely throughout the Indo-Pacific including Guam, the Philippines, Australia, and the Indian Ocean. in less than 20 m depth. Found and photographed by Cory Pittman.We DO know something about the etymology of its name, of course. Notice that on the side of the animal, are large bivalved pedicellariae, which are sort of like big clamps that sit on the lateral side of the animal (see white circles below). Hence Valvfor the valves on each pedicellariae and -aster for star.. And the adjective striatus refers to the striated patterns on the body surfaceColor in this species varies....This one is darker with green where others are more red...This animal was from Guam and is a borrowed image from Gustav Paulay's excellent FMNH site on Indo Pacific animals.Note that this one in Wikipedia? NOT Valvaster (looks like an oreasterid or a goniasterid). Pls. make a note of it!

Monday, January 11, 2010

Today a cool pic of an uncommonly seen starfish from Hawaii! Coscinasterias acutispina!

The animal was found by Pauline Fiene and was photographed by nature photographer Cory Pittman (and should be copyright by him). Both Pauline and Cory oversee the cool Sea Slugs of Hawaii site.

Coscinasterias acutispina is an asteriid-that is, its related to those common intertidal starfish, such as Asterias or Pisaster that feed on mussels and clams on the east and west coasts of North America.The beast above was observed in Kahului Harbor in Maui. It's about 30 mm in diameter and was found at less than 3 m depth, under rubble. These have been reported from Hawaii in the past, but have been so infrequently encountered that they are actually absent from the excellent Hawaiian Sea Creatures book by John Hoover.

Generally, starfishes in the family Asteriidae occur in cold-water regions like Antarctica or Alaska, but every so often-you get a couple that pop up in temperate to tropical shallow waters. For various reasons, asteriids and other forcipulatacean starfish don't generally live in tropical shallow-waters. So, seeing one outside of temperate water is unusual.

Coscinasterias occurs rather widely though, and you can find other species from New Zealand to the tropical Atlantic...Here's some basic taxonomic info..This species also occurs in Japan, China, Australia, and other regions throughout the Indo-Pacific. Here is a pic of this species from Japan....

Monday, January 4, 2010

Welcome to the first post of the new year! I thought I would kick-off the year with a new kind of post!

Many of you know that as a taxonomist, I am happy (when i have the time) to identify images of various species that are sent to me from YOU the public. BUT up until recently, I performed this service privately. I am one of the few people in the world who can ID these beasts with some authority, so my time to do "freebies" is at a premium.

So, I was thinking that pics of animals I identify CAN (and should?) BE SHARED with the PUBLIC!

and so here we are.

Today's beast is member of the Goniasteridae, called Iconaster longimanus. A beautiful animal that is found in the central Indo-Pacific, including the Philippines, Singapore, the South China Seas, Indonesia, SE Arabia, and in Northern and western Australia, including Queensland in 6-85 meter depths. You can find a paper I wrote about the taxonomy of Iconaster here.

Today's picture was provided by marine photographer Franca Wermuth, whose website can be found here.My understanding is that she's normally a nudibranch afficionado, but has now added starfish to her list of interests! The animal above was photographed in the Philippines from Romblon (Romblon Province, Romblon Island), next to Lugbung Island in about 35 meters depth. Water temperature was 27.2°.
Relatively little is known about Iconaster's biology. Its name Icon is from the Greek eikon for portrait or image, and possibly refers to the way the marginal plates form a frame around the edge. And -aster of course refers to the word "star".

Its species name longimanus translates into "long hands" which clearly makes reference to the extended arms.

The icon star (Iconaster longimanus) is a striking species that occurs on lower reef slopes and the adjacent sea bed around many of the Southern Islands. It feeds on epilithic growth on hard substrata and coral rubble. Zoologically, it is interesting as it has large lecithotrophic eggs which show abbreviated development, without a larval stage. In recent years this sea-star has been found to be moderately common on and around many of the reefs fringing the Southern Islands. However it is considered vulnerable because living on and near the slopes of fringing reefs, it is threatened by reclaimation activities. Additionally, its attractive appearance many lead to over collection as a curio. Such threats are of particular concern given its slow growth rates.

About Me

I pursue starfish related adventure around the world with a critical eye and an appreciation for weirdness.
Support has been courtesy of the National Science Foundation but the views and opinions presented herein are mine and do not reflect the opinions of them or any affiliated institutions.
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